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Vestibular Neuritis

Synonyms:

Neurolabyrinthitis, acute unilateral peripheral vestibulopathy

Definition:

Vestibular neuritis is defined as a disorder in which there is sudden, spontaneous, isolated, total or subtotal loss of afferent vestibular input from one labyrinth. This condition is one of the commonest causes of spontaneous vertigo.

Etiology:

Viral infection of the vestibular nerve has been attributed to be the cause. Herpes simplex type I virus proteins have been demonstrated using PCR in these patients. In majority of cases of vestibular neuritis the superior division of the vestibular nerve is affected. The bony canal through which the superior division will have to travel is longer and narrower than that of the inferior division, thus making it more vulnerable to inflammatory insults.

Clinical features:

1. Acute spontaneous vertigo

2. Associated with nausea and vomiting

3. Intensity of vertigo increases by the hour

4. Can be minimized by keeping the head still

5. Aggravated by active movements of head

6. When attempting to walk the patient becomes unsteady and sways towards the side of affected labyrinth

7. Symptoms gradually subside over the following days

Many patients may have residual imbalance which could last for months.

During the acute phase these patients manifest with spontaneous horizontal torsional nystagmus. This nystagmus is unilateral, with the quick component beating towards the unaffected side. This nystagmus gets suppressed by visual fixation, and hence can be missed totally unless the visual fixation is removed.

Head impulse test: In this test the subject is asked to look at the nose of the examiner. The head is rotated to one side. In healthy subjects during the head rotation the eyes of the patient stays fixed on the nose of the examiner. In patients with vestibular neuritis, movement of head towards the affected side, the vestibulo ocular reflex is defective, hence the eye also moves towards the side of motion. This results in correcting saccadic movement of the eye when it attempts to refocus on the nose of the examiner.

Vestibular neuritis is a clinical diagnosis. Electronystagmography can be performed to record the nystagmus.